From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5E853C433FE for ; Fri, 15 Oct 2021 08:20:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 485AD61163 for ; Fri, 15 Oct 2021 08:20:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235023AbhJOIWq (ORCPT ); Fri, 15 Oct 2021 04:22:46 -0400 Received: from szxga03-in.huawei.com ([45.249.212.189]:25190 "EHLO szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230518AbhJOIV6 (ORCPT ); Fri, 15 Oct 2021 04:21:58 -0400 Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.57]) by szxga03-in.huawei.com (SkyGuard) with ESMTP id 4HVzgM32rvz8tY1; Fri, 15 Oct 2021 16:18:39 +0800 (CST) Received: from dggema762-chm.china.huawei.com (10.1.198.204) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Fri, 15 Oct 2021 16:19:48 +0800 Received: from [10.174.176.73] (10.174.176.73) by dggema762-chm.china.huawei.com (10.1.198.204) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Fri, 15 Oct 2021 16:19:47 +0800 Subject: Re: [patch v8 0/7] handle unexpected message from server From: "yukuai (C)" To: , , , CC: , , , References: <20210916093350.1410403-1-yukuai3@huawei.com> <37b222c1-d6b0-3e46-248a-2557db40ae92@huawei.com> <5effbc3a-e2f5-063f-6a20-985016d390c6@huawei.com> Message-ID: <326edfba-01d3-9921-de9a-24134c592012@huawei.com> Date: Fri, 15 Oct 2021 16:19:47 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <5effbc3a-e2f5-063f-6a20-985016d390c6@huawei.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.176.73] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To dggema762-chm.china.huawei.com (10.1.198.204) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/10/08 15:17, yukuai (C) wrote: > On 2021/09/29 20:54, yukuai (C) wrote: >> On 2021/09/23 21:33, yukuai (C) wrote: >>> On 2021/09/16 17:33, Yu Kuai wrote: >>> >>> Hi, jens >>> >>> Any interest to apply this series? >> >> friendly ping ... > > Hi, Jens > > friendly ping again ... Hi, Jens friendly ping again ... >>> >>> Thanks, >>> Kuai >>>> This patch set tries to fix that client might oops if nbd server send >>>> unexpected message to client, for example, our syzkaller report a uaf >>>> in nbd_read_stat(): >>>> >>>> Call trace: >>>>   dump_backtrace+0x0/0x310 arch/arm64/kernel/time.c:78 >>>>   show_stack+0x28/0x38 arch/arm64/kernel/traps.c:158 >>>>   __dump_stack lib/dump_stack.c:77 [inline] >>>>   dump_stack+0x144/0x1b4 lib/dump_stack.c:118 >>>>   print_address_description+0x68/0x2d0 mm/kasan/report.c:253 >>>>   kasan_report_error mm/kasan/report.c:351 [inline] >>>>   kasan_report+0x134/0x2f0 mm/kasan/report.c:409 >>>>   check_memory_region_inline mm/kasan/kasan.c:260 [inline] >>>>   __asan_load4+0x88/0xb0 mm/kasan/kasan.c:699 >>>>   __read_once_size include/linux/compiler.h:193 [inline] >>>>   blk_mq_rq_state block/blk-mq.h:106 [inline] >>>>   blk_mq_request_started+0x24/0x40 block/blk-mq.c:644 >>>>   nbd_read_stat drivers/block/nbd.c:670 [inline] >>>>   recv_work+0x1bc/0x890 drivers/block/nbd.c:749 >>>>   process_one_work+0x3ec/0x9e0 kernel/workqueue.c:2147 >>>>   worker_thread+0x80/0x9d0 kernel/workqueue.c:2302 >>>>   kthread+0x1d8/0x1e0 kernel/kthread.c:255 >>>>   ret_from_fork+0x10/0x18 arch/arm64/kernel/entry.S:1174 >>>> >>>> 1) At first, a normal io is submitted and completed with scheduler: >>>> >>>> internel_tag = blk_mq_get_tag -> get tag from sched_tags >>>>   blk_mq_rq_ctx_init >>>>    sched_tags->rq[internel_tag] = sched_tag->static_rq[internel_tag] >>>> ... >>>> blk_mq_get_driver_tag >>>>   __blk_mq_get_driver_tag -> get tag from tags >>>>   tags->rq[tag] = sched_tag->static_rq[internel_tag] >>>> >>>> So, both tags->rq[tag] and sched_tags->rq[internel_tag] are pointing >>>> to the request: sched_tags->static_rq[internal_tag]. Even if the >>>> io is finished. >>>> >>>> 2) nbd server send a reply with random tag directly: >>>> >>>> recv_work >>>>   nbd_read_stat >>>>    blk_mq_tag_to_rq(tags, tag) >>>>     rq = tags->rq[tag] >>>> >>>> 3) if the sched_tags->static_rq is freed: >>>> >>>> blk_mq_sched_free_requests >>>>   blk_mq_free_rqs(q->tag_set, hctx->sched_tags, i) >>>>    -> step 2) access rq before clearing rq mapping >>>>    blk_mq_clear_rq_mapping(set, tags, hctx_idx); >>>>    __free_pages() -> rq is freed here >>>> >>>> 4) Then, nbd continue to use the freed request in nbd_read_stat() >>>> >>>> Changes in v8: >>>>   - add patch 5 to this series. >>>>   - modify some words. >>>> Changes in v7: >>>>   - instead of exposing blk_queue_exit(), using percpu_ref_put() >>>>   directly. >>>>   - drop the ref right after nbd_handle_reply(). >>>> Changes in v6: >>>>   - don't set cmd->status to error if request is completed before >>>>   nbd_clear_req(). >>>>   - get 'q_usage_counter' to prevent accessing freed request through >>>>   blk_mq_tag_to_rq(), instead of using blk_mq_find_and_get_req(). >>>> Changes in v5: >>>>   - move patch 1 & 2 in v4 (patch 4 & 5 in v5) behind >>>>   - add some comment in patch 5 >>>> Changes in v4: >>>>   - change the name of the patchset, since uaf is not the only problem >>>>   if server send unexpected reply message. >>>>   - instead of adding new interface, use blk_mq_find_and_get_req(). >>>>   - add patch 5 to this series >>>> Changes in v3: >>>>   - v2 can't fix the problem thoroughly, add patch 3-4 to this series. >>>>   - modify descriptions. >>>>   - patch 5 is just a cleanup >>>> Changes in v2: >>>>   - as Bart suggested, add a new helper function for drivers to get >>>>   request by tag. >>>> >>>> Yu Kuai (7): >>>>    nbd: don't handle response without a corresponding request message >>>>    nbd: make sure request completion won't concurrent >>>>    nbd: check sock index in nbd_read_stat() >>>>    nbd: don't start request if nbd_queue_rq() failed >>>>    nbd: clean up return value checking of sock_xmit() >>>>    nbd: partition nbd_read_stat() into nbd_read_reply() and >>>>      nbd_handle_reply() >>>>    nbd: fix uaf in nbd_handle_reply() >>>> >>>>   drivers/block/nbd.c | 135 >>>> +++++++++++++++++++++++++++++++------------- >>>>   1 file changed, 96 insertions(+), 39 deletions(-) >>>>